Haplosporidium pinnae Detection from the Faeces of Pinna nobilis: A Quick and Noninvasive Tool to Monitor the Presence of Pathogen in Early-Stage or during Fan Mussel Mass Mortalities

Due to the increasing mass mortality of Pinna nobilis, mainly caused by the protozoan Haplosporidium pinnae along the Mediterranean Sea, it is necessary to develop rapid and effective methods to detect the pathogen. The present study describes the development and validation of a species-specific assay based on hydrolysis probe chemistry to detect H. pinnae DNA from faeces and pseudofaeces of P. nobilis. During a study campaign in the Gulf of Trieste (Italy) in the spring and summer of 2022, 18 samples (10 faeces and 8 pseudofaeces) were collected. DNA was isolated from all samples and the presence of H. pinnae was tested by amplifying a small portion of 18S rDNA using qPCR. The newly developed assay detected positive H. pinnae in the faeces of the fan mussel in the spring, while no evidence of an outbreak of H. pinnae was found in the summer. In addition, the method proved to be noninvasive and can be used to monitor suspected H. pinnae infections in the early stages when bivalves are still vital. Furthermore, fecal analysis allows the monitoring of P. nobilis without dissecting tissues. The presented assay can also be used to routinely monitor the progress of mass mortalities caused by H. pinnae and to screen for the pathogen in live fan mussels and other environmental matrices, such as water, sediment, and faeces from other species that can host the protozoan

Sink or swim? Modernization of mussel farming methods may negatively impact established seabird communities

Marine aquaculture is the fastest growing sector of global food production and is projected to increase to meet future demand. Expansion and modernization of cultivation methods are needed to reach this target but a cost-benefit evaluation for biodiversity conservation is required to achieve sustainable aquaculture practices. We assess drivers of avian richness and abundance in a long-established seabird community present in a series of longline mussel farms in Italy and in response to a recent modernization process in the farming methodology. Over 2 years (24 surveys) we detected a remarkable diversity (15 species in 5 families) and abundance (n = 5858) of birds, of which 40% (n = 6) are regarded as species of international conservation importance. Our models highlighted that the strongest driver explaining variation in abundance and richness across sites was the type of buoy and the associated cultivation method applied. The older and fast-declining double headrope design, offered greater stability for birds to rest. Conversely, the newer and mechanizable single headrope design dominant method in our study site and projected to replace the older system, was unsuitable for birds. Our findings confirm the function of mussel farms as a sort of marine protected area where low anthropogenic disturbance, higher prey availability and suitable artificial structures promote the establishment of seabird communities with minimal impacts on harvest. However, we suggest that potential modernization of farming methods, important to meet future human demand, needs to be carefully assessed and compensated for, particularly where long-established seabird communities have formed in response to such practices